Biomedical response exercise equipment which avoids interference effects

ABSTRACT

A monitor-exercise equipment apparatus for measuring a biomedical response such as heartbeat rate, and for using the measured response to control the exercise equipment, where the monitor includes a transmitting unit and a receiving unit located in the exercise equipment. The monitor detects a biomedical condition such as heartbeats and produces a pulse train representing this response. The pulse train is then encoded to produce an encoded signal having a first identification part identifying the transmitting unit and a second data part representing the person&#39;s biomedical response. This encoded signal is wirelessly sent to the receiving unit which reads the received signal to determine if it is from the transmitting unit. If it is from that transmitting unit, the data part is read. If the received signal is not from the correct transmitting unit, it is rejected. Interference from other monitors or electrical equipment is minimized, and the data displayed is very accurate. The receiving unit provides a signal to a parameter control in the exercise equipment. The parameter control automatically regulates the resistance offered to the user in accordance with the measured heart rate of the user to provide a proper workout. Memory is included for providing exercise profiles unique to the user. An identification unit allows each user to identify himself/herself to the equipment to access the proper stored exercise profile for that person.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of Ser. No. 08/684,302 filed Jul. 18, 1996, nowU.S. Pat. No. 5,913,827 which is a continuation of Ser. No. 08/380,370filed Jan. 30, 1995, now U.S. Pat. No. 5,538,007, which is acontinuation of Ser. No. 08/065,564 filed May 21, 1993, now U.S. Pat.No. 5,394,879, which is a continuation in part of Ser. No. 08/033,826filed Mar. 19, 1993, now U.S. Pat. No. 5,400,794.

FIELD OF THE INVENTION

This invention relates to controlled exercise using an apparatus formonitoring a physical condition or body response such as heart rate, andmore particularly to controlled exercise equipment in which errors dueto interfering sources are minimized or eliminated and in which improvedaccuracy results due to error detection and correction in the patternrepresenting the body response.

BACKGROUND ART

For many applications, it is necessary to measure and display a person'sbody response, such as his or her heartbeat. In particular, in exerciseand fitness training, it is often the situation that a person wishes tomeasure his or her heartbeat in order to achieve the maximum benefits ofthe exercise without the danger of increasing the heartbeat to a ratewhere adverse effects could occur. Of course, such measurements are alsouseful for many health applications such as biofeedback and exerciseprograms where the participants only mildly exercise and do not approachgreatly elevated heart rates. Over the years, various types of equipmenthave been marketed for the measurement of heart rate, such instrumentsbeing popular in a wide variety of applications extending from all formsof exercise to biofeedback. Continuous accurate heart measurement is animportant part of all aerobic exercise and rehabilitation programs andfor this reason many types of apparatus have been commercially availablefor personal use by individuals and in fitness clubs, etc. Some of thisequipment includes heart rate monitors that are used to control theintensity of the workout based on the user's measured heart rate. Aswill be discussed later, the problem of providing a good monitornecessarily affects the quality of an exercise program that is responseto a measured heart rate.

Some of the most popular heartbeat monitor designs use wireless datatransmission from a sensor-transmitter unit to a display unit. This typeof design allows optimal and flexible positioning of both units whilenot limiting a person's freedom of movement. Unfortunately, theincreasing popularity of heart measurement, and therefore the use ofthese heart monitors, has demonstrated the limitations of currentlyavailable designs. An example is the recurring interference effectsbrought about when a person wearing a heart monitor is in closeproximity to another person wearing another heart monitor. These peoplerun the risk that their individual monitor readings are influenced bythe monitor worn by the other person. Further, it is equally frustratingfor a person wearing a heart monitor to find that electromagneticequipment of all types, such as exercise equipment, power lines etc.will create electromagnetic fields that interfere with the successfultransmission of his or her heartbeat, thereby causing an erratic displaywhich is uncorrectable without moving away from the interfering exerciseequipment, power lines, etc.

Various types of wireless measuring methods have been proposed. Some ofthese are based on radio waves while others use a magnetic proximityfield. Most of these prior techniques transmit an analog ECG signal of aperson. However, as noted, these prior techniques and apparatus are notsimultaneously usable by several persons in close proximity to oneanother or by person who are using such apparatus in close proximity toelectrical or electronic equipment. In such cases, the reliability oftransmission of heartbeat is significantly reduced with the result thata continuous and accurate monitoring of the heartbeat is no longerpossible. As is readily appreciated, this lack of reliability is aproblem for anyone using the monitor and is especially disconcerting toa person who is exercising to a level where his or her heartbeat isclose to the maximum desired for that person.

Examples of some prior art monitors include U.S. Pat. No. 4,625,733;U.S. Pat. No. 4,425,921; U.S. Pat. No. 3,212,496; and U.S. Pat. No.3,949,388. The first of these describes a heartbeat monitor using amagnetic proximity field as a basis for analog wireless transmission,where a particular arrangement of magnetic coils is used in thetransmitter and the receiver units.

U.S. Pat. No. 4,425,921 describes a portable heartbeat monitor which canbe used to check either pulse rate or heart rate using separate sensorsfor detecting heartbeat and pulse beat. The apparatus shares a commonindicator for displaying the heartbeat rate or pulse beat rate dependingupon a switch means for connecting either of the sensors to amicrocomputer. Analog signals are used in this monitor, which does notuse wireless transmission between a transmitter and receiver.

U.S. Pat. No. 3,212,496 describes an apparatus for simultaneouslymeasuring ECG, respiration rate, and respiration volume. A pair ofelectrodes on or in a person's body have current passed therebetween andsense an impedance change and a heartbeat voltage. A frequency modulatedsignal can then be telemetered to a receiving and display unit.

U.S. Pat. No. 3,949,388 describes a portable apparatus that can be usedfor analog biomedical telemetry, and is particularly adapted for use ina hospital where each sensor-transmitter unit is used on a singlepatient and will not normally be used on another patient. Thetransmitter is designed to produce a very narrow frequency spectrumwhere a steady pulse rate accurately represents the measured temperatureof the patient. In order to avoid interference from adjacent units, thereceiver unit is located within only a few feet of the transmittingunit. Further, a very low power continuously sending transmitting unitis used so that only the closest receiver will detect the analog signal.This avoids the possibility that the receiver will pick up signals fromanother transmitter. Thus, the selectivity of the receiver is based onits close proximity to the associated transmitter unit, not on anycircuitry which would prevent interference by a transmitter broadcastinga high power signal, even though such interfering transmitter may be faraway. Further, the frequency range intended for operation is selected tobe very narrow. As noted in this patent, frequency sweeping can occurdue to saturation of a transistor in the oscillator circuit. In order toprevent this undesirable frequency sweeping, an isolating impedance isused in the circuit design to prevent feedback current of the type whichcauses the transistor saturation.

U.S. Pat. No. 5,157,604 describes a hospital monitoring system in whichmany patient transmitter units are coupled to a central station.Wireless transmission of a signal including an identifier and heartbeatdata occurs from each patient unit to the central station. Each patientunit transmits on its own frequency so there will be no interferencebetween the patient units. The responses of the patient units are timemultiplexed, since these units respond to the central station only inresponse to the receipt of a timing signal from the central station.Error detection and correction of an incorrect heartbeat due to faultytransmission is not mentioned.

In the prior art monitors for measuring and displaying heartbeat, it isusually not possible to provide a technique and apparatus fordetermining if the received signal in the display unit is from theproperly associated transmitter unit or is instead from anothertransmitter unit. Further, if there are errors occurring in the datarepresenting the heartbeat, such as missing portions of the signal dueto interference from outside sources, the display in these priormonitors will either indicate a wrong value, not indicate heartbeat, ormaintain the previous reading without making the user aware of theproblem. In these prior art monitors, there is no way to account fortransient errors in heartbeat which are momentarily caused but which donot necessarily render inaccurate the later readings of heartbeat. Ifthese prior art monitors are used to control exercise equipment, thereis a problem due to interference from the motors in the equipment andalso from other monitors on equipment that is closely located to theuser's exercise equipment.

It is therefore a primary object of the present invention to provide animproved technique and apparatus for monitoring and displaying abiomedical function (body response) such as heartbeat, wherein theabove-described problems are addressed and corrected and to provideexercise equipment using this improved apparatus.

It is another object of the present invention to provide exerciseequipment using an improved personal use heartbeat monitor whichautomatically rejects interfering signals from sensor-transmitter unitsother than the one with which the display unit is properly associated.

It is another object of the present invention to provide a heartbeatmonitor in which the presence of transient errors in the signalrepresenting the heartbeat does not render inaccurate the heartbeatdisplayed to the person wearing the monitor, where this monitor is usedto control exercise equipment in accordance with the person'sinstantaneous heart rate.

It is another object of this invention to provide a wireless heartbeatmonitor which can be easily worn by a person engaged in all forms ofphysical exercise, and which will nonetheless provide accuratemeasurement of the person's heartbeat even in the presence of otherheartbeat monitors and/or electrical or electronic equipment in whichcomponents of the monitor are located.

It is another object of the present invention to provide exerciseequipment in which a part of a person's ECG signal is digitally encodedfor wireless transmission to a receiver-display unit located in theexercise equipment, where the coding allows a receiver-display unit toidentify the encoded digital signal as having been sent from aparticular sensor-transmitter unit.

It is another object of the present invention to provide exerciseequipment using a heartbeat monitor which will automatically change thefrequency range over which signals representing the heartbeat arewirelessly sent from a sensor-transmitter unit to a receiver-displayunit, the transmission frequency being changed in response to theoccurrence of errors in the received signal.

It is a further object of this invention to provide a technique andapparatus for monitoring heartbeat where the monitor is used in exerciseequipment without adversely affecting the accuracy of the data displayedto the person using the monitor.

It is another object of this invention to provide improved exerciseequipment for isolating monitor signals relating to a biologicalfunction, such as heartbeat, wherein the monitored signals are digitallyencoded to provide user identifiers that are wirelessly transmitted.

It is a still further object of this invention to provide automatictransmission error detection and correction in a wireless biologicalresponse monitoring system used to control exercise equipment inaccordance with a user's biological response.

BRIEF SUMMARY OF THE INVENTION

This invention broadly relates to exercise equipment that uses animproved technique and monitor for measuring and displaying, preferablyon a continuous basis, a physical condition or biomedical response, suchas a heartbeat rate. The monitor includes a transmitter unit forproducing an encoded digital signal representing the biomedical responseand for wirelessly transmitting the encoded digital signal to a receiverunit for display of the measured biomedical response. The monitor alsoincludes a detection means for detecting errors in the received encodeddigital signal, and correction means for automatically changing thetransmitter unit and the receiver unit to provide accurate wirelesstransmission therebetween of the measured biomedical response. In apreferred embodiment this monitor includes unique identification betweena transmitter and an associated receiver.

This monitor is particularly suitable for personal use such as wouldoccur in a home or office or even in a gym or fitness center where itcan be a part of exercise equipment. In one embodiment, the transmitterunit is adapted to be worn and would be battery operated while thereceiver unit can be part of exercise equipment and can be used tocontrol a workout in response to a measured biological response. As longas the receiver is within the transmission distance from thetransmitter, it will receive the wirelessly transmitted signal. In oneaspect of this invention the monitor measures a person's heartbeat anddisplays an indication of the monitored heartbeat. In this embodiment,the apparatus is comprised of a sensor-transmitter unit (chest unit)adapted to be worn in contact with a person's chest and havingelectrodes which receive the person's ECG signal. This signal isamplified and digitally encoded to contain an identification portion anda data portion. This encoded signal is transmitted in a wireless mannerto a receiver-display unit (wrist unit), where the receiver-display unitcontains a display for displaying the person's heartbeat. While thereceiver-display portion of the monitor can be adapted to be worn, forexp. on a person's wrist, this unit need not be worn and could belocated elsewhere, for example on exercise equipment. In the inventionof this continuation-in-part application the receiver-display unit isused to control the exercise equipment in response to a continuousmonitoring of the exercising person's biological response (heart rate,etc.). Further, while chest electrodes generally provide the best ECGsignals, the transmitter unit could be placed elsewhere, such as on aperson's wrist.

Because the person's ECG signal is digitized and encoded, two purposescan be achieved. The first is that an identification is provided whichis different for each heart monitor. That is, after the receiver-displayunit receives the transmitted encoded signal, it checks this signal tosee if it contains the proper identification code. If this comparisonfails, the incoming signal to this unit is not accepted because it isnot from the proper chest unit. However, if the identification compareswith the reference identification in the receiver unit, the incomingsignal will be accepted. This prevents two heart monitors working inclose proximity to each other and transmitting on the same frequencyfrom receiving and displaying signals from the wrong person.

The second purpose of the digital encoding is to provide transmissionerror detection and correction of the heartbeat data. In practice, it ispossible that a valid signal may be rejected by the receiver-displayunit due to an outside noise source. The data portion of the transmittedsignal is therefore encoded into a particular bit sequence. When theincoming data bit sequence is checked against a reference data bitsequence in the receiver-display unit, errors in the received signal canbe detected. The receiver unit can be set so that infrequently occurringerrors (such as transient errors) will be corrected but not result in achange of the transmitting and receiving units. On the other hand, iftoo many errors are present, the receiver unit will notice it andprovide a frequency change signal to change the transmission frequencyin the chest unit and also to change the receiving frequency in thereceiving unit. In a preferred embodiment the power of the frequencychange signal is also increased to ensure that the frequency change ismade. While the receiving unit will automatically cause a change infrequency if persistent errors occur, the user can also change thetransmission and reception frequency if it is anticipated that a problemmay occur. This feature of a change in transmission and receivingfrequency also allows the use of multiple units in close proximity toone another without reciprocal disturbances.

The chest unit generally contains an input sensor means for receivingthe ECG signal, amplifying means, comparator means for producing adigital pulse train corresponding to the analog ECG pulses, encodermeans for encoding the digital pulse train into coded signals havingbits corresponding to an identification portion and further bitscorresponding to a data portion of said encoded signal, and means toreceive a frequency change signal from the wrist (receiving) unit forchanging the transmitting frequency of the chest unit. This latter meansincludes a receiver for receiving via wireless transmission thefrequency change signal from the receiving unit when the transmissionfrequency is to be changed and a signal evaluator for reading theidentification code in the frequency change signal to determine that itis from the associated receiving unit and for providing a signal to thetransmitter means for changing the transmission frequency for theoutgoing signals from the chest unit. Part of the identification signalmay serve for synchronization of a clock signal in the receiving andtransmitting units.

The receiving unit broadly includes a receiver for receiving outputsignals from the chest unit and a signal evaluator for separating theidentification portion and the data portion of the incoming encodedsignal and for determining if the incoming signal is from the associatedchest unit. The signal evaluator also checks the data portion of theincoming signal to determine if it has the proper data pattern for theassociated chest unit. The signal evaluator provides an output to amemory means for storing heartbeat data and also provides an output thatis sent to a display, for displaying the heartbeat rate. The signalevaluator further provides an output that is sent to a transmitter meanslocated in the receiving unit if the signal evaluator determines thatthe frequency of errors in the data portion of the incoming signal isbeyond a given bound, that is, if the bit patterns indicate that theerrors are not merely transient but are sufficiently repetitive as toprovide potentially inaccurate monitoring of person's heartbeat. Theoutput of the transmitter means in the receiving unit is sent in awireless manner to the receiver in the chest unit. At the same time, thesignal evaluator also provides a signal to the receiver in the receivingunit to change its reception frequency to match the new transmissionfrequency in the chest unit. The receiving unit also contains an inputterminal by which the user can directly initiate a change intransmitter/receiver frequency, or can block an automatic change offrequency in the chest and receiving units. For example, the user maysense that the external condition which is causing an error in thereceived encoded signal will soon cease so that it is not necessary tochange frequency. Another situation where a user may want to prevent afrequency change is where there are multiple users in close proximity.Rather than have everyone's monitor change frequency, some monitors canbe held at fixed frequencies while other monitors change frequency.

This design will overcome most of the limitations of the currentlyavailable wireless heart monitors. Additionally, it will compensate forminor errors and enable the user to avoid certain error sources bypurposely changing the transmission frequency. Of course, the user canallow the monitor to automatically change frequencies. Since the rangeof the human heart rate is fairly restricted, this design allows thedetection of uncorrectable errors by taking into account the elapsedtime between two successful data transmissions. Since it is highlyimprobable that the wrist unit will receive the correct identificationpattern from a source other than the associated chest unit, the user canhave a very high level of confidence in the accuracy of the displayedheart rate. This is accomplished even though the chest and receivingunits are separate from one another and communication therebetween isvia wireless transmission.

The invention uses the improved monitor to control exercise equipment inresponse to a measured biomedical function such as heart rate. Thereceiving unit is located on the exercise equipment and provides acontrol signal to change (increase or decrease) or maintain theresistance offered to the user by the exercise equipment. Thisresistance is changed in accordance with the measured heart rate (forexp.) in a continuous manner to provide an exercise workout includingwarm-up, cool-down and sustained aerobic exercise.

Memory means and a microprocessor are used to maintain an up-to-dateprofile of the exercising person and to continuously regulate theresistance of the equipment in accordance with the user's instantaneousheart rate. Identification means allows the user to identify himself orherself to the exercise equipment in order to have the equipment accessthe proper exercise profile from memory. Additional memory is providedto allow the user to enter a different exercise profile if it is notdesired to user the exercise profile already stored in memory. An inputcontrol to the microprocessor allows the user to override any profilecontrol that the microprocessor would usually select.

The invention is most useful in the case of personal use equipment whichallows the user to have complete mobility while undergoing heartbeatmonitoring. The various components of the chest and wrist units areeasily provided by known microelectronic integrated circuit chips thatcan be packaged together in small volume and battery operated. The majoruse of this monitor will be for continuous display during personalactivities by an individual, including exercise, biofeedback, andgeneral health monitoring. In these activities wireless transmissionwill be over a relatively short range, particularly if both thetransmitter and receiver units are worn or if the receiving unit islocated in the exercise equipment.

These and other objects, features, and advantages will be apparent fromthe following more particular description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the heart rate monitor of thepresent invention, showing the chest unit (transmitting unit) and thewrist unit (display) which receives the signal from the chest unit via awireless transmission and displays the heartbeat of the person beingmonitored.

FIG. 2 shows a typical ECG signal and the train of digital pulsesrepresenting each of the analog pulses in the ECG signal.

FIG. 3A shows a typical format of the encoded digital signal wirelesslytransmitted from the chest unit to the wrist unit, this digital signalconsisting of a synchronization part, an identification part unique tothis particular chest monitor and a data part unique to the person'sheartbeat.

FIG. 3B represents a sequence of bits corresponding to the data part ofthe outgoing digital signal from the chest unit (FIG. 1) where each datapart is represented as a two-bit binary code in this example.

FIG. 4 is a schematic illustration of the chest unit in more detail,showing the various components of this unit.

FIG. 5 is a schematic illustration of the wrist unit in more detail,showing the components comprising this unit.

FIG. 6 is a schematic illustration of a modified chest unit, where theencoded digital signal represents the full heartbeat rate.

FIG. 7 schematically illustrates the user of this inventive monitor tocontrol exercise equipment in accordance with a user's heart rate.

FIG. 8 shows the various components of the receiver-controller unit inthe exercise equipment depicted in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The practice of this invention will be represented by the example of aheartbeat monitor, where it is desired to accurately measure heartbeatand to provide a technique which eliminates many of the errors found inthe use of presently available wireless heartbeat monitors, particularlythose of the portable type adapted to be used by people undergoingexercise, biofeedback etc. Such problems generally relate tointerference effects that can occur if two wireless heartbeat monitorsare operating in close proximity to one another, noise attributable tosources other than another heart monitor, confusion between receivedsignals wherein the heartbeat being displayed may not be that of theperson being monitored and situations where the user would be unawarethat the displayed heartbeat is inaccurate.

FIG. 1 schematically represents the heartbeat monitor 10, which iscomprised of a chest unit 12 (transmitting unit) and a complementarywrist unit 14 (receiving or display unit). Wireless transmission over aplurality of frequency ranges can occur from chest unit 12 to wrist unit14, as represented by the arrows 16. Wireless transmission from thewrist unit 14 to the chest unit 12 is used to correct transmissionerrors but usually over only a single frequency as represented by thesingle arrow 17. As will be described later, wireless transmission fromthe display unit 14 to the chest unit 12 will occur when it is desiredto change the transmission frequency from the chest unit. This can bedone either automatically or on command by the user. In practice, thetransmitter of the chest unit is frequency matched to the receiver inthe wrist unit so that an encoded digital signal wirelessly transmittedfrom the chest unit 12 will be correctly received by the wrist unit 14.

FIG. 2 illustrates a typical ECG signal 18 from a person beingmonitored, and the digital pulse train 20 corresponding to the ECGsignal. Each digital pulse corresponds to the onset of a positive slopeportion 22 of the analog pulses forming the ECG signal train 18. As analternative, each digital pulse can correspond to another portion of theanalog pulses, such as the peak of each pulse. In the present invention,the ECG signal is digitized prior to wireless transmission from thechest unit 12 to the wrist unit 14. The purpose of this apparatus is tomonitor heartbeat and therefore it is sufficient to transform the ECGsignal into a digital pulse train. The particular characteristicsrelating to a person's ECG signal are not of importance in the presentinvention.

Prior to the transmission of a digital signal from chest unit 12 towrist unit 14, the digital signal is given a specific binaryidentification sequence. Further, the individual digital pulses in thepulse train 20 are each encoded into m bits. A sequence of digitalpulses will therefore result in a sequence of these m bit signals. Thissequence is predetermined and is known to the wrist unit 14. A certainbit sequence can precede the identification portion with the encodeddigital signal to facilitate synchronization of the transmitter andreceiver. FIG. 3A shows a typical format of the encoded digital signaltransmitted from the chest unit 12 to the wrist unit 14 where the signalis comprised of a 3 bit synchronization part, an 8 bit identificationpart and a two bit data part. FIG. 3B shows a sequence of four digitalpulses represented by a code having two bits per pulse, i.e., m=2. Inthis sequence, the first encoded group 00 represents the first digitalpulse, the second encoded group 01 represents the second digital pulse,the third encoded group 11 represents the fluid digital pulse, and thenext encoded group 10 represents the fourth digital pulse. This pattern,and its order, will be used each time the ECG signal is sampled andencoded. The pattern and its order will be changed if m is changed.

In operation, it is possible that a transmission error can occur.Sometimes these errors are only transient, in which case the lastdisplay reading will be maintained. It can also be the situation thatthe errors continue to occur due to interference from some outsidesource (such as an adjacent heartbeat monitor) where the errors are, forexample, missing bits during repeated transmissions. Since the writeunit 14 knows the predetermined code for the data portion of the signal,the missing of up to 2^(m)−1 continuous signals will be immediatelynoticed and the missing signals can be accounted for. If too manysignals (>2^(m)−1) are missing and therefore the interference is not atransient one, the frequency of the transmitter and receiver will bechanged automatically. This can also be done on demand by the user.Thus, encoding of the digital pulse train 20 to include anidentification part and a data part enables the receiving unit to acceptonly those signals sent from the associated chest unit and to detect andcorrect errors in the data part corresponding to the person's heartbeat.Details of how this occurs will be explained with respect to theapparatus of FIG. 4 (chest unit) and FIG. 5 (wrist unit).

Heartbeat Monitor Technique

This section will describe in general terms the technique of the presentinvention in which heartbeat monitoring is achieved in an advantageousmanner. In a first step, a person's ECG signal is detected and thensufficiently amplified. This amplified signal is transformed into adigital pulse signal which can be used to initiate the wirelesstransmission of an encoded digital signal from the chest unit 12 to thewrist unit 14. The digital signal being transmitted includes anidentification part and a data part as illustrated in FIG. 3A. Thetransmitted encoded data signal is received by a complementary receiverin wrist unit 14 and transformed therein back into the encoded digitalsignal. The resulting digital signal is separated into itsidentification part and its data part. Wrist unit 14 verifies theidentification sequence to determine that he received signal is from theproper chest unit. If not, the signal is not accepted. If theidentification step is satisfied, the data portion of the receivedsignal is then checked to see whether it has the expected value. If theexpected value is present in the received signal, then the displayportion of the wrist unit is updated. Some or all of the data can alsobe stored in a memory contained in the wrist unit. As an option, thedata can be first sent to the memory prior to being displayed.

The data portion of the transmitted encoded signal can represent a fullheartbeat rate, or just a portion of it. For example, the number of ECGpulses in a 3-second interval can be represented. If this number ismultiplied by 20, the approximate heartbeat rate in beats per minutewill be known. This calculation can be done in the receiver unit or inthe transmitter unit if the full heartbeat rate is to be transmitted tothe receiver.

If the full heartbeat rate is transmitted, then less transmissions willbe needed. In turn, this means that there will be less likelihood ofinterference from other sources and less power will be consumed. Ofcourse, the number of transmissions in a given time from the transmitterto the receiver can be determined as a design parameter in accordancewith considerations such as power, likelihood of interference, clockingrequirements, etc. Various coding schemes are well known for selectingthe number of ECG pulses to sample and the sampling repetition rate. Inthe practice of this invention, any of these known coding schemes, or adifferent one, can be chosen.

If the sequence of bits forming the data portion of the received signalis not maintained in the expected sequence, an error has occurred andthe number of missing digital pulses is determined. These missingdigital pulses are assumed to be evenly distributed in a correspondingtime range and the display will be updated and/or the data will bestored in memory together with some annotation about the error.

In this embodiment, the occurrence of a certain number of errors>2^(m)−1 with a given time frame means that the indicated heart beatrate will be unreliable. This will result in an automatically generatedrequest for a frequency switch that is initiated in the wrist unit 14.This request for a change in transmission frequency can be blocked bythe user or can be initiated on demand by the user. For example, theuser may see that he or she will be in the presence of others usingheartbeat monitor devices or maybe near exercise or other types ofequipment which would interfere with the signals being transmitted fromthe chest unit. Knowing that such an interference may occur and mayextend for a period of time, the user may wish to change thetransmission frequency in order to avoid problems. Alternatively theuser may recognize that any interference will be only transient, andtherefore may wish to block a frequency change. In actual use, mostpersons would allow the monitor to automatically adjust. The amount oferrors that will trigger a frequency change is a parameter that can bevaried, according to the logic incorporated in the monitor.

If a change in transmission frequency is needed, a digital signal(frequency change signal) will be sent via wireless transmission fromthe wrist unit to the chest unit. This digital signal can include anidentification part and a data part which specifies the new transmissionfrequency. The identification part of this digital signal allows thechest unit to know that the frequency change signal has been sent fromthe associated wrist unit and is therefore a correct command to changefrequency. At the same time, the wrist unit changes the frequency of thereceiver in this unit to match the new transmitter frequency of thechest unit 12. The transmission path from the wrist unit 14 to the chestunit 12, commanding a new transmission frequency, is not often used.However, once it is used the probability of a correct transmission mustbe high. For these reasons, it is preferable that there be only onepossible transmission frequency for this path and that this transmissionfrequency be different from the frequencies used on the maintransmission path, i.e., the transmission frequencies normally used totransmit the encoded digital signals from the chest unit to the wristunit 14. As a further measure to increase the reliability of the secondtransmission path from the wrist unit 14 to the chest unit 12, the powerof the frequency change signal from the wrist unit to the chest unit ishigher than the power normally used for the transmission of encodeddigital signals from the chest unit 12 to the wrist unit 14. Thisensures that the necessary frequency change in the main transmissionpath will be made.

The following description will detail the components comprising thechest unit 12 and the wrist unit 14, which together comprise theheartbeat monitor 10.

Chest Unit (FIG. 4)

FIG. 4 shows the various components of chest unit 12 which are used todetect an ECG signal, amplify that signal and digitize it, encode itinto an identification portion and a data portion, and then towirelessly transmit it to wrist unit 14. The chest unit also includesmeans for receiving a frequency change signal from the wrist unit thatwill trigger a change in transmission frequency of the outgoing signals.

In more detail, chest unit 12 is typically carried on the breast of thetarget person such that this person's ECG signal 18 can be received bythe input electrode terminals 24. These terminals 24 can be a part ofthe chest unit or the chest unit can be designed so that any sensor fordetecting a biomedical response can be plugged into it. The ECG signal18 is then amplified in a differential amplifier 26, producing theamplified signal represented by arrow 28. Amplified signal 28 istransformed into a digital pulse train 20 (FIG. 2) in the comparator 30,which has hysteresis. This hysteresis feature prevents the generation ofmore than one digital pulse from one heartbeat, due to outsidedisturbances of any type. The correlation between the ECG signal 18 andthe digital pulse signal 20 was described with respect to FIG. 2.

The digital pulse signal 20 is sent directly to the transmitter 37 vialine 32, and is also sent to an encoder means 34 via interconnectionline 36. The rising flank of a digital pulse will trigger transmittingmeans 37 to wirelessly transmit an encoded electromagnetic signal 16 toa receiving means in the wrist unit 14. The rising flank of a digitalpulse also triggers encoder 34 to provide the synchronization part, theidentification part and the data part of the encoded digital signalrepresented by arrow 38 which is transmitted by the transmitting means37. The digital pulse on line 32 is used only as a clock or timingpulse. Line 32 can be eliminated in an alternative design whereinclocking is internal in transmitter 37 or is provided by a portion ofthe encoded signal from encoder 34.

Encoded digital signal 38 is shown in FIG. 3A, while a sequence ofsignals corresponding to the encoded data portion is shown in FIG. 3B.Every digital pulse in pulse train 20 (FIG. 2) results in advancing onestep in the cycle of the encoded data signals. Therefore, FIG. 3Billustrates a pulse sequence corresponding to four digital pulses in thepulse train 20. Only a small and predetermined number of encoded signalsmust be transmitted by transmitting means 37.

Chest unit 12 also contains a receiver 40 and a comparator 42, termed asignal evaluator. Units 40 and 42 are used to receive a frequency changesignal from wrist unit 14 indicating that a transmission frequencychange is required, and to thereby provide a signal to the transmission37 to achieve this. In more detail, if errors beyond a given bound arenoted in the data portion of the incoming digital signals in the wristunit 14, a transmitted frequency change signal 17 will be wirelesslysent to chest unit 12 and is received by the receiver 40. This receivedsignal contains the binary identification pattern unique to thisheartbeat monitor and a data portion which will trigger a change infrequency. In this embodiment, chest unit 12 need not be equipped witherror detection and correction means. It is only necessary that the dataportion of the frequency change signal indicate that a new transmissionfrequency is desired. The data portion can also specify this newfrequency or logic in signal evaluator 42 can specify the new frequencyrange over which the encoded digital signals will be sent.

The frequency change signal is sent to the comparator 42 (signalevaluator) which compares the coded identification pattern in thereceived digital signal with the coded identification pattern for thisheartbeat monitor 10. As noted, this identification pattern is unique tothis heartbeat monitor. If the comparison shows that the identificationportion of the incoming signal matches that for this heartbeat monitor,comparator 42 will determine the new transmission frequency from thedata portion of the received signal and will generate a digitalfrequency select signal 44 that is sent to the transmitter 37. As willbe explained later, a signal evaluator in the wrist unit will provide acorresponding signal to a receiver therein in order that the receptionand transmission frequencies will be matched.

Wrist Unit 14 (FIG. 5)

FIG. 5 illustrates the components which make up the wrist unit 14(display). This unit provides the general functions of receiving theencoded digital signal representing a person's heartbeat, comparing theidentification portion of the encoded signal to the appropriatereference identification pattern, and displaying and/or storing the datarepresenting this heartbeat. Another function that is accomplished is acheck of the data portion of the encoded signal to determine if anyerrors therein are within an acceptable bound or, if they are not,generating a signal to change the transmitter frequency as well as thefrequency of the receiver in the wrist unit. As noted, this errordetection and correction means takes into account transient errors whichdo not repeat and for which a frequency change is not required as wellas persistent errors which necessitate a change in transmissionfrequency in order to provide accurate data transmission. In thiscontinuation-in-part application, the “wrist” unit is located in theexercise equipment and is used to control the part of the equipmentwhich regulates the resistance offered to the user.

In more detail, wrist unit 14 contains a receiver 46 for receiving theencoded digital signals 16 from chest unit 12, a comparator or signalevaluator 48 for analyzing the received encoded signals, a memory unit50 in which data representing heartbeat can be stored, a display unit 52for displaying to the user his or her heartbeat, and a transmitter 54for the wireless transmission of frequency change signals to the chestunit in order to change the frequency of transmission.

The electromagnetic signal 16 is received by receiver 46 and transformedinto a digital signal that is sent to the comparator 48. This digitalsignal is identical to the outgoing digital signal transmitted fromchest unit 12 to wrist unit 14. In the comparator 48, the receiveddigital signal is separated into its identification part and its datapart. The identification part of the signal is compared to the presetand unit-specific identification unique to this heartbeat monitor. Ifthe identification part of the incoming signal does not match thereference identification part, the incoming signal is ignored. If thereis a match, comparator 42 then checks whether the data portion of theincoming signal is in the proper pattern order shown for example, inFIG. 3B for a situation in which m=2. If the data bit sequence matchesthe reference sequence, then the transmission from the chest unit 12 tothe wrist unit 14 was error free and the necessary signal evaluation canbe done. This means that the information can be sent directly to display52 and/or stored in memory 50.

If the data portion is not the expected pattern, the number of missingpatterns is determined. This number also gives information about theseverity of the transmission error. The necessary approximations tocompensate for this error are then done in the signal evaluation unit 48in order to compensate for the error. For example, if only one bit ismissing from the expected pattern, the signal evaluator would havebuilt-in logic that would provide the bit so that the heartbeat ratecorresponding to that data pattern would be displayed. If the error is amajor one but does not repeat itself, the signal evaluator will causethe last displayed heartbeat rate to remain displayed.

If the occurrence of transmission errors is beyond a given bound thenthe signal evaluator unit will automatically generate a frequency changesignal 56. This signal will be sent to the transmitter 54 for wirelesstransmission (represented by arrow 17) to the receiving means 40 inchest unit 12 (FIG. 4). The selection of the new transmission frequencytakes into account the recent history of transmission failures for thevarious frequencies. This can be done by a table look-up feature insignal evaluator 48 where the number of transmission errors is storedfor each of the transmission frequencies. Signal evaluator 48 alsoprovides a frequency change signal 58 to the receiver 46. This enablesreceiver 46 to have a receiving frequency matching that of the newfrequency used in the transmitter 37 (FIG. 4).

As an alternative, the user can use input terminal 60, which isconnected to the signal evaluator 48, in order to either block thechange of frequency or to initiate a change in frequency.

Normally a change(s) in transmission frequency will provide accuratedata to the receiving unit. However, if the monitor detects errors thatcontinue to occur after several frequency changes, the internal logic inthe monitor will prevent the further display of heartbeat rate (blankscreen) and/or will provide an alarm signal. In this way, the user isnot fooled by the display of an inaccurate heartbeat as occurs withpresently available monitors.

The data evaluation leading to information for updating the display canbe sent to the memory 50 besides being entered into the display 52.Later this stored data can be displayed in the display 52.Microprocessor 62 would control the flow of heartbeat data from memory50 to display 52. Display 52 can be of the visual type such as the LCDdisplay and/or can be audible, as for example an alarm or other soundrepresenting a heartbeat count.

The transmitter-receiver pair 37-46 can communicate on severalfrequencies and uses a relatively low power signal in order to preservebattery life. The transmitter-receiver pair 54-40 communicates on onlyon frequency and uses a relatively high power signal, in a preferredembodiment. This takes into account that the transmitter-receiver pair37-46 is in constant use and that hardware is provided for errordetection and correction. In contrast, the transmitter-receiver pair54-40 is only rarely used and the monitor 10 has no errordetection/correction facility with respect to the encoded signalrepresenting a frequency change selection.

The transmitter 54 will continue transmitting an electromagnetic signal17 until a correct electromagnetic signal 16 is delivered by transmitter37 to receiver 46 in the wrist unit. If for some reason thissynchronization fails, the user can synchronize the chest and wristunits by external means.

FIG. 6 illustrates a modification of the transmitter unit which isparticularly adapted for wireless transmission of the full heartbeatrate. The same reference numerals will be used in this figure as wereused in FIG. 4, for components having the same or similar functions. Ofcourse, the unit of FIG. 4 can also be used to encode and transmit thefull heartbeat rate.

In more detail, the transmitter of FIG. 6 includes the amplifier 26,comparator 30, encoder 34, transmitter 37, receiver 40 and signalevaluator 42 shown also in FIG. 4. However, a timer 64 is now used totrigger the transmitter 37 for wireless transmission of the encodeddigital signal from encoder 34. In this embodiment, a data check circuit66 is used to enable error detection and correction of the encodeddigital signal prior to its being transmitted to the receiver unit. Forexample, this can be done by use of a parity bit. This helps to ensureaccuracy if the entire heartbeat rate is to be transmitted, particularlyif the heartbeat rate is not transmitted at a high repetition frequency,i.e., if there is a long time duration between each wirelesstransmission of heartbeat rate. The receiver unit of FIG. 5 can be usedto receive and evaluate the full heartbeat rate sent by the transmittingunit.

Many different types of encoding can be used to represent theidentification and data portions of the transmitted signals. Also, therate of sampling of the ECG pulses can be varied, as can the repetitionrate at which wireless transmissions of the encoded digital signal aremade. The frequency change signal used to trigger a new transmissionfrequency can be transmitted over a multiple frequency range rather thanover a single selected frequency. The frequency ranges used in the maintransmission path can be chosen by the designer in accordance with knownprinciples of wireless transmission, which in personal use monitors isof a short range.

As noted, the principles of digitization of the transmitted heartbeatsignal, transmission frequency changes, and signal encoding to ensurethe accuracy of the communicated results are used to provide personaluse monitors far superior to those presently being marketed. However,such principles may be applied to other than personal use monitors. Itis recognized, though, that the provision of such features is unique ina wearable heartbeat monitor where the monitor includes a wearabletransmitting unit and an associated display unit. These features arealso unique to monitors where the display (receiver) unit is located onexercise equipment or is a small unit that can be placed in a suitablelocation for viewing by the user. Such units are distinguishable fromlarge hospital units wherein a central computer is used to coordinate amultiplicity of transmitting and/or display units.

While the monitor has been illustrated in an embodiment thereof formonitoring heartbeat rate, it will be understood by those of skill inthe art that a signal indicative of another physical condition can bemonitored. For example, an acoustical sensor can detect a pulse or athermometer sensor can detect a temperature. This type of monitor can beapplied to measure and display any type of life function, in persons oranimals. Additionally, wireless monitors for measuring physicalconditions other than life functions can utilize the principles of errordetection and correction described herein.

While it has been mentioned that the display (receiver) unit can belocated on exercise equipment, the monitor can be used for controllingintensity and type of workout on exercise equipment based oncontinuously monitoring a body response of the target person. Forexample, the exercise equipment can be programmed to receive acontinuous heart rate response of the target person and then adjust theintensity (such as resistance) of the exercise to maintain the person'sheart rate within a preselected range.

The monitor of this invention is particularly suitable for use withexercise equipment since it is insensitive to the closeness of otherexercise equipment, motors within the equipment being used by theperson, and other closely located monitors operating on the same orclose frequency ranges. This allows the receiver-display unit to belocated anywhere on the exercise equipment without concern forinterference effects which would yield the wrong heart rate andcorrespondingly provide an incorrect workout.

It is well known that exercising in a correct amount plays an essentialrole in any effort to fight cardiovascular disease and certain forms ofcancer. However, the best result can only be achieved when the correctway of exercising is selected. In the past, this has led to certainrules of thumb such as exercising at 70% of the maximum heart rate,where the maximum heart rate is given by the expression (220 minus age).In order to obtain this, a constant monitoring of the heart rate duringexercise is required and there must be an adaptation of the intensitylevel of the exercise based upon the heart rate. As the heart rate of aperson depends on a variety of daily factors such as sleep, diet, healthetc., it is not sufficient to determine the best type and intensity ofexercise for a person only one time, e.g., in a doctor's office, andthen stay with the level over a long period of time. Additionally, thetraining effect of exercise itself leads to a gradual shift in theexercise level which is best suited for the individual.

Until only recently, the control of the intensity level of the exerciseequipment was left completely to the exercising person. Even when theperson had an accurate heart monitor he/she still had to adjust theintensity of the exercise according to the reading on the monitor. Onlyin closely supervised programs such as those undertaken by professionalathletes or persons in a cardiac rehabilitation program was this tasktaken over by a trainer or a doctor.

Since exercise equipment is now used in many forms of exerciseactivities, it is appropriate to incorporate some means of exerciselevel control into the equipment. A first step has been done by somecompanies which offer exercise bikes allowing the constant measurementof heart rate as long as the exercising person touches two electrodeswith his/her hands. The measured heart rate is then used by the bikecontrol circuit to increase or reduce the resistance of the bike inorder to keep the heart rate of the target person within a selectedrange.

Although this type of exercise bike is certainly a step in the correctdirection, this equipment has several significant disadvantages. Whileit may be somewhat inconvenient, a target person can probably beconvinced to keep a firm grip on the handles of the exercise bike.However, this technique cannot be used for other kinds of exerciseequipment such as treadmills or stairclimbers, where a constant contactof the skin with electrodes on the equipment cannot be guaranteed. It isalso doubtful that this technique can be generalized to be used formeasuring other body responses, such as blood pressure. Further, thistype of heart monitoring does not allow for warm-up and cool-down phaseswhich are essential in the design of proper exercise. In some cases,doctors will even suggest that for person with limited available timethat the exercise should consist only of a warm-up and cool-down phase.In such an event, the aforementioned exercise bike will not provide theproper workout.

As the heart rate is supposed to change during the phases of warm-up,aerobic workout, and cool-down, a more complex control mechanism isnecessary than for a phase in which a constant target heart rate issought. Further, in an exercise bike, like in many other exerciseequipments, there are often multiple parameters which determine theintensity of the exercise. For the exercise bike, these parameters arethe pedal speed and the resistance. In presently available exercisebikes, only the resistance is controlled by the heart rate. Stillfurther, these exercise bikes cannot keep track of the exercise historyof the target person and take this into account in deriving the bestexercise type and level. Although the heart rate has a very shortresponse time to a change in exercise intensity, this may not be thecase for other body responses. If there is a significant delay between achange in the exercise intensity and a corresponding change of the bodyresponse, this must be anticipated by a more complex control algorithm;that is, the exercise equipment control should not be restricted to afeedback type regulation but should also incorporate a feed-forwardcontrol in which the equipment parameters are adjusted ahead of time inorder to eliminate excess overshoots and undershoots of the measuredbody response.

There are also some exercise bikes being marketed which use wirelessmonitors to measure heart rate of the exercising person and to use thatheart rate to adjust the exercise work load. In some instances,different exercise programs can be incorporated into the equipment,where these programs have predetermined resistance levels to simulatehills or flat terrains.

FIG. 7 schematically illustrates the user of the present monitor withexercise equipment, in this case an exercise bike. The transmitter unitof the monitor is located on the person while the receiver unit islocated on the exercise equipment. The receiver includes a display whichindicates the biomedical response, such as heart rate, and also providesan electrical signal for controlling one or more exercise parameters,such as pedal rate and resistance. In FIG. 7, the transmitter unit 12provides a digitally encoded signal 16 in a wireless manner to thereceiver 14, which is coupled to the display and controller in theexercise bike 70.

The use of a wireless transmission ensures that the user will not beconstrained in his freedom of body movements regardless of the type ofexercise equipment that is employed. The features of error detection anderror correction, together with the means for changing transmissionfrequency allow accurate heart rates to be transmitted even in roomswhich are crowded with exercise equipment or with numerous peoplewearing heart rate monitors.

It is desirable that the exercise profile of the present exercise to bederived from an input from the user. An already stored history of thisspecific user and the baseline of the user's body response will providemore appropriate exercise. Of course, the user can also override thisfeature and enter his own profile. In this invention, the whole exerciseprofile including the warm-up and cool down and any other intervalportions are continuously adjusted depending upon the measurement of thebody response.

The receiver-controller unit on the exercise equipment is operated inresponse to the measured biomedical function, such as heart rate. Asdifferent parameters of the exercise equipment may employ differentmuscle groups, the composition of the parameter selection will depend onthe exercise history of the target person. For example, both arms andlegs may be subject to different exercises, each of which will affectheart rate.

For each exercise run, key characteristics of this run will be stored inmemory and used in refine the exercise profile of the same person. Sincethis requires a technique to distinguish between different persons usingthe exercise equipment, identifiers are used as are used with thedigitally encoded signal (i.e., the identification portion).

A microprocessor in the exercise equipment will take into account thepresent and previous heart rates of the person and make these ratessubject to a weight function in order to give the most consideration tomost recent heart rate, but not to disregard the previous heart rates.For instance, the same present heart rate must result in differentactions if it is a sudden increase over the previous heart rates or ifit is the same as the previous heart rate or even a decline in heartrate. After the exercise run, the key characteristics of the run areextracted and stored in a memory of the equipment to be available forfuture exercise activity of the same person.

FIG. 8 shows the various components of the receiver-controlled unit.This unit can include the various components shown on FIG. 5, where FIG.8 shows the receiving means 46 for receiving the digitally encodedsignal 16 from the transmitting unit 12. Although it is not shown inFIG. 8, the receiver/controller unit would include the transmitter 54(FIG. 5) used to change frequency if there is excess interference. Thefunctions of the other components (signal evaluator 48, memory 50,display 52, input terminal 60, and microprocessor 62 of FIG. 5) areprovided by the components shown in FIG. 8.

Microprocessor 72 is a major component of the receiver-controller andprovides the logic, signal recognition and identification, andinstructions to the exercise parameter control unit 74 for controllingthe exercise intensity in accordance with a desired exercise profilebased on the target person, the type of exercise to be undertaken, andthe time period for the exercise.

A magnetic strip reader 76 is used as an identification means in orderto identify the target person. Other forms of identification could alsobe used, including a keyboard entry of a coded identifier. The purposeof this component is to identify the exercising person to the equipmentso that the receiver in the receiver-control unit will be synchronizedwith the transmitting unit assigned to that user. Further, the use of aninput device, such as a magnetic strip card which can be read by reader76, enables a person to load his or her personal data into an internalmemory 78 so that a proper profile can be assigned by microprocessor 72.It may be that the internal memory 78 already has stored informationrelative to that user which can be directly implemented by themicroprocessor 72 in establishing the exercise parameter control unit 74for a particular resistance, pedal speed, elevation, etc. depending uponthe type of exercise equipment to be used (exercise bike, stairclimber,etc.).

A console input 80, such as a keyboard mechanism or remote control, isalso electrically connected to the microprocessor 72. The console inputunit 80 allows the user to manually control the exercise parametershe/she wishes to employ, thereby overriding the profile control that themicroprocessor 72 would normally adopt. Console input 80 allows the userto deviate from programmed control of the exercise equipment at any timedepending on personal needs and desires.

Console display 82 receives inputs from microprocessor 72 and displaysthe person's heart rate. Displays are also for indicating exerciseparameters such as pedal speed, resistance, elevation, etc., as well astime, height, weight, age etc. In a normal program, one third of thecomplete exercise time would be used for warm-up and one third would beuse for cool down. The remaining one third would be used to provide anexercise regimen at the desired heart rate, which could, for example, beat an aerobic rate (about 70% of the desired maximum heart rate for thatindividual.

Internal memory unit 78 contains stored programs for the operation ofthe microprocessor, including those programs which enable it to analyzethe incoming digitally encoded signal in order to read theidentification part, error correction part, and heart rate data portion,as described previously. Memory 78 also provides storage of data of theuser at that time, including the user's previous workout data. Theadvantage of internal memory 78 is that it enables thereceiver-controller unit to recognize the past performance of a personin order to better control fluctuations that might be seen when a newexercise program starts. In this manner, the microprocessor 72 will notcall for radical changes of the exercise parameter control 74 due tononsignificant changes in heart rate. For example, it may be that aperson's heart rate jumps to a high level very quickly in the warm-upphase of exercise, and thereafter stabilizes. Having this data ininternal memory 78 prevents the microprocessor from radically decreasingthe resistance, etc. of the exercise equipment which would not providethe proper warm-up for this type of person. Of course, the user canoverride any preprogrammed profile by using the console input 80.

An external memory unit 84, using for example a magnetic or opticaldisk, provides a universal way for allowing any piece of exerciseequipment to be used by any individual. For example, a person can takehis/her disk to any gum and enter a desired profile using the externalmemory unit 84 which interacts with the microprocessor 72. When this isdone, there will be an override of any profile program from internalmemory 78, or the user can elect to use a default program stored ininternal memory 78.

The following will now detail the use of exercise equipment operatedunder control of the receiver-controller unit of FIG. 8, where thebiomedical response is illustratively a heart rate as measured andwirelessly transmitted using the monitor of this invention. Inoperation, the user first identifies himself at the console of theexercise equipment prior to the exercise, e.g., by entering a passwordor by using the magnetic strip reader 76. If there already exists anexercise history file for this user, the user is asked to enter someinformation about the exercise which he/she plans to do. Thisinformation is entered using the console input unit 80 and may includethe planed exercise time and the type of exercise, such as intervaltraining or cardiovascular workout. The user can also override theautomatic profile generation stored in internal memory 78 by enteringhis/her own intensity or heart rate profile. This can be done, forexample, by inserting the user's disk in the external memory reader 84.If there is no exercise history file for the user in internal memory 78and no stored data is entered using unit 84, the user is asked to entervarious personal data such as age, weight, height, gender etc. Thesedata will then be stored in the exercise history file of the user ininternal memory 78, and will be used for his/her future exercises. Theuser then receives various default profiles from which to choose. Theseprofiles will include a warm-up time, a cool-down period and a period oftime in which an aerobic heart rate will be maintained.

The user then attaches the heart rate monitor to the appropriate bodypart, usually the chest, and takes the desired position on the exerciseequipment without starting exercising. The microprocessor 72 controlswhether a heart rate is obtained and whether the transmission isreliable, that is, whether the heart rate is not fluctuating in a largerange or is outside the expected range. If anything unusual isregistered, the user is asked to take corrective action, such asmoistening the electrodes of the transmitter unit. The user can alsooverride this feature if he/she is convinced that everything is fine andif the user knows that his/her heart rate is unusually high or low.

After this, the user is asked to start exercising. The first short timeframe of low intensity exercise is used for the microprocessor 72 toestablish a baseline for the user. This baseline reflects the presentstate of the user and thus considers momentary health, possible lack ofsleep, diet etc. Based on this baseline and on the selected exerciseprofile, microprocessor 72 makes a preliminary assignment of exerciseparameters to time points during the exercise run and the expected heartrate.

After these preliminaries, the user starts higher exercise. The heartrate is continuously monitored and transmitted to the receiver 46 in theexercise equipment. Receiver 46 transfers the data to the microprocessor72 wherein the integrity of the data is checked. If the data passes thisintegrity check, meaning that no error has been detected, the measuredheart rate is used to adjust the exercise intensity level based on thedeviation of the measured heart rate from the projected heart rate. Ifthe exercise equipment has several parameters to be set, for examplepedal rpm and resistance in an exercise bike, the user receives aproposed value for a parameter that he/she can control. For example, theuser can set the pedal rpm at 80 rpm while the other parameter(resistance) is adjusted by the receiver-controller in accordance withthe continuously monitored heart rate. If it can be detected that theuser cannot maintain the suggested parameter, the proposed parameter ismodified. For example, the proposed pedal rpm value can be reduced to70. If microcomputer 72 detects a sequence of errors in the receiveddata, it notifies the user via the console display 82 that is cannot anylonger control the run based on the measured heart rate. Microprocessor72 then gives the user the choice to continue the exercise run withoutthis control or to gradually stop the exercise. This operation runsunder control of instructions received from internal memory 78. If theheart monitor senses recurrent errors beyond that which can be correctedby the error detection and correction means, a frequency change is usedto determine another frequency in which correct wireless transmission ofthe correct heart rate will be obtained.

After the exercise run, microprocessor 72 will extract the keycharacteristics of the exercise, such as maximum heart rate after aspecified exercise time, the relevant intensity level, warm-up andcool-down times, and baseline values at the beginning and at the end ofthe exercise run. These key characteristics will be stored in internalmemory in the exercise history file for the specific user. They can alsobe written into an external memory disk placed in thereceiver-controller external memory unit 84.

In contrast with existing equipment, the apparatus shown in FIGS. 7 and8 uses a microprocessor and associated memories to store backgroundinformation indicative of a particular person, and uses identificationmeans to tailor an exercise run to a user's specific profile. Further,this equipment is based on an instantaneous heart rate measurement atall times, not just on a single set heart rate or on preprogrammed timesfor setting various exercise levels. Because the monitor of thisinvention provides error detection and correction, and because it hasthe capability of changing frequency in order to eliminate interferenceeffects, it can be used on all types of exercise equipment and in thepresence of many users in the same exercise room. That is, the proximityof many users wearing heart monitors and closely spaced motor-drivenexercise equipment will not lead to errors. This is particularlyimportant where the exercise run is being controlled throughout its timeduration in accordance with a continuously monitored heart rate. Thus,the use of the monitor of this invention to provide continuous controlexercise equipment offers several unique features and advantages.

While this invention has been described with respect to particularembodiments thereof it will be apparent to those of skill in the artthat variations may be made without departing from the spirit and scopeof the present invention, which is to be measured only by the appendedclaims. Body responses other than heart rate, such as temperature, bloodpressure etc. can also be used to automatically control exercise usingthis monitor.

What is claimed is:
 1. An apparatus for controlled exercise of a user,including: a sensor for obtaining an ECG signal from a user of exerciseequipment; means for determining the heartbeats of said user from saidECG signal, means for producing encoded signals representing at leastone heartbeat of said user, said encoded signals also providing anidentification signal, a transmitter for transmitting said encodedsignals to a receiver, said identification signal being shared betweensaid transmitter and said receiver, identification means in saidreceiver for using said identification signal to determine if saidencoded signals are from said transmitter, rejection means in saidreceiver for rejecting said encoded signals if said encoded signals arenot from said transmitter, means for determining heartbeat rate fromsaid received encoded signals if said encoded signals are from saidtransmitter, exercise equipment having a parameter control therein foradjusting a parameter that affects the exercise workout of said user,said parameter control receiving a signal representing heartbeat rateand having means therein for adjusting said exercise workout in responseto said signal representing heartbeat rate.
 2. The apparatus of claim 1,further including input means for enabling said user to vary saidexercise workout independent of said signal represent heartbeat rate. 3.The apparatus of claim 1, further including a display for displayingsaid user's heartbeat rate.
 4. The apparatus of claim 1, furtherincluding detection means for detecting errors in said received encodedsignals and correction means for correcting said errors.
 5. Theapparatus of claim 4, further including means for changing the frequencyover which said transmitting occurs if the number of errors exceeds apredetermined amount.
 6. The apparatus of claim 1, further includingstorage means for storing the arrival times of said encoded signals insaid receiver, test means in said receiver for testing whether therecent pattern of arrival times of said encoded signals matchesexpectations for a sequence of heartbeats and means for calculatingheartbeat rate based on the recent arrival times of said encodedsignals.
 7. The apparatus of claim 1, where said means for determiningthe heart beats of said user is connected to said sensor.
 8. Theapparatus of claim 7, further including detection means for detectingerrors in said received encoded signals and correction means forcorrecting said errors.
 9. An apparatus for controlled exercise of auser, including: a sensor for obtaining ECG signals from a user ofexercise equipment, means for producing encoded signals from said ECGsignals, each said encoded signal including a data signal used todetermine heartbeat rate and an identification signal, a transmitter fortransmitting said encoded signals to a receiver, said identificationbeing shared between said transmitter and said receiver, identificationmeans in said receiver for using said identification signal to determineif each said encoded signal is from said transmitter, rejection means insaid receiver for rejecting said encoded signal if it is not from saidtransmitter, means for determining heartbeat rate from said receivedencoded signals if said received encoded signals are from saidtransmitter, exercise equipment having a parameter control therein foradjusting a parameter that affects the exercise workout of said user,said parameter control receiving a signal representing heartbeat rateand having means therein for adjusting said exercise workout in responseto said signal representing heartbeat rate.
 10. The apparatus of claim9, where said means for determining heartbeat rate is in saidtransmitter.
 11. The apparatus of claim 10, further including inputmeans for enabling said user to vary said exercise workout independentof said signal representing heartbeat rate.
 12. The apparatus of claim10, further including a display for displaying said user's heartbeatrate.
 13. The apparatus of claim 9, further including detection meansfor detecting errors in said received encoded signals and correctionmeans for correcting said errors.
 14. The apparatus of claim 13, furtherincluding means for changing the frequency over which said transmittingoccurs if the number of errors exceeds a predetermined amount.
 15. Anexercise apparatus, including exercise equipment, a sensor for obtainingECG signals from a user of said exercise equipment, means for producingencoded signals from said ECG signals, a transmitter for transmission ofsaid encoded signals to a receiver, a receiver on said exerciseequipment for receiving said encoded signals from said transmitter,identification means for determining if said encoded signals are fromsaid transmitter, rejection means in said receiver for rejecting saidencoded signals if said encoded signals are not from said transmitter,means for calculating said user's heart rate, and display means locatedon said exercise equipment for displaying said user's heart rate. 16.The apparatus of claim 15, where said encoded signals represent theuser's heartbeats.
 17. The apparatus of claim 16, wherein said means forcalculating heart rate is in said receiver.
 18. The apparatus of claim17, further including detection means for detecting errors in theencoded signals received in said receiver and means for correcting saiderrors.
 19. The apparatus of claim 18, where said correction meansincludes means for correcting for missing portions of said encodedsignals in said receiver.
 20. The apparatus of claim 15, where saidmeans for calculating the user's heart rate is in said transmitter. 21.The apparatus of claim 15, where said encoded signals include anidentification portion which is shared between said transmitter and saidreceiver, said identification portion being used by said identificationmeans for determining if said encoded signals in said receiver are fromsaid transmitter.
 22. The apparatus of claim 21, where said encodedsignals are a series of pulses.
 23. The apparatus of claim 15, wheresaid means for producing encoded signals from said ECG signals isconnected to said sensor.
 24. The apparatus of claim 23, where saidencoded signals represent the user's heartbeats.
 25. The apparatus ofclaim 24, where said means for calculating heart rate is in saidreceiver.
 26. The apparatus of claim 25, further including detectionmeans for detecting errors in the encoded signals received in saidreceiver and means for correcting said errors.
 27. The apparatus ofclaim 26, where said correction means includes means for correcting formissing portions of said encoded signals in said receiver.
 28. Theapparatus of claim 23, where said means for calculating the user's heartrate is in said transmitter.
 29. The apparatus of claim 23, where saidencoded signals include an identification portion which is sharedbetween said transmitter and said receiver, said identification portionbeing used by said identification means for determining if said encodedsignals in said receiver are from said transmitter.
 30. The apparatus ofclaim 29, where said encoded signals are a series of pulses.
 31. Anapparatus for exercise based on a human biomedical condition includingin combination: means for detecting signals indicative of saidbiomedical condition and for producing first signals used to determinesaid biomedical condition of a person using said apparatus, atransmitting unit connected to said means for detecting, saidtransmitting unit including means for producing an identification signalidentifying said transmitting unit, said transmitting unit alsoincluding a transmitter for wirelessly transmitting said first signalsand said identification signal to a receiver located on a piece ofexercise equipment, exercise equipment having a parameter control meanstherein for adjusting a parameter that affects the exercise workout ofsaid person, a receiver located on said exercise equipment for receivingsaid identification signal and said first signals, processor means forreading said identification signal to determine the identity of thetransmitting unit from which said first signals and said identificationsignal are sent and for producing a control signal to said parametercontrol means in response to said person's biomedical condition if saidfirst signals have been sent from said transmitting unit, said parametercontrol means being responsive to said control signal for adjusting saidparameter in response to the biomedical condition of said person.
 32. Amethod for controlled exercise of a person in response to continuousmonitoring of a person's heart rate, including the steps of: providingexercise equipment having a parameter control means therein for changingor maintaining the resistance offered by said exercise equipment to auser of said equipment, producing first signals used to determine theuser's heart rate, wirelessly transmitting said first signals from atransmitter to a receiver located on said exercise equipment, receivingsaid wirelessly transmitted first signals at a receiver located in saidexercise equipment, determining if said received first signals are fromsaid transmitter, even in the presence of interference, using saidreceived first signals, if said received first signals are from saidtransmitter, to develop control signals that are sent to said parametercontrol means located in said exercise equipment, said control signalsdetermining the resistance offered by said exercise equipment to saiduser, said control signals being related to the heartbeat rate of saiduser.
 33. An apparatus for controlled exercise of a user, including: asensor for obtaining an ECG signal from a user of exercise equipment,means connected to said sensor for determining the heartbeats of saiduser from said ECG signal, means for producing encoded signalsrepresenting said user's heart rate, a transmitter for transmitting saidencoded heart rate signals to a receiver, rejection means in saidreceiver for rejecting signals if said signals are not from saidtransmitter, exercise equipment having a parameter control therein foradjusting a parameter that affects the exercise workout of said user,said parameter control receiving signals representing the user'sheartbeat rate and having means therein for adjusting said exerciseworkout in response to said signal representing heartbeat rate.
 34. Theapparatus of claim 33, further including detection means for detectingerrors in said encoded signals and means for compensating for saiderrors.
 35. The apparatus of claim 33, where said encoded signals aredigitally encoded.
 36. The apparatus of claim 33, further including adisplay for displaying said user's heart rate.
 37. An exercise apparatuscomprising: exercise equipment, a sensor for obtaining signals relatingto heartbeats from a user of said exercise equipment, means connected tosaid sensor for using said signals to produce encoded signals of saiduser's heartbeat rate, a transmitter for transmission of said encodedsignals to a receiver, a receiver on said exercise equipment forreceiving said encoded signals from said transmitter, rejection means insaid receiver for rejecting signals that are not from said transmitter,and display means on said exercise equipment for displaying said user'sheartbeat rates.
 38. The apparatus of claim 37, further including meansfor detecting errors in said received encoded signals.
 39. The apparatusof claim 38, further including means for compensating for said errors.40. The apparatus of claim 39, where said encoded signals are digitallyencoded.
 41. The apparatus of claim 37, where said encoded signalsinclude pulses used to identify said transmitter to said receiver.
 42. Amethod for controlled exercise of a person in response to continuousmonitoring of a person's heart rate, including the steps of: providingexercise equipment having a parameter control means therein for changingor maintaining the resistance offered by said exercise equipment to auser of said equipment, producing encoded signals of the user's heartrate, wirelessly transmitting said encoded signals from a transmitter toa receiver located on said exercise equipment, receiving said wirelesslytransmitted encoded signals at a receiver located on said exerciseequipment, using said received encoded signals, if said received encodedsignals are from said transmitter, to develop control signals that aresent to said parameter control means located in said exercise equipment,said control signals determining the resistance offered by said exerciseequipment to said user, said control signals being related to theheartbeat rates of said user.
 43. The method of claim 42, where saidencoded signals are digitally encoded.
 44. The method of claim 42,further including a display on said exercise equipment for displayingsaid user's heartbeat rate.
 45. An apparatus for exercise based on auser's heart rate, comprising: a sensor for detecting body signalsrelating to said user's heartbeats, encoding means connected to saidsensor using said body signals to produce a series of encoded signalsrepresenting said user's heart rates, a transmitter for transmittingsaid encoding signals representing heart rates to a receiver located ona piece of exercise equipment, exercise equipment having a parametercontrol means therein for adjusting a parameter that affects theexercise workout of said user, a receiver located on said exerciseequipment for receiving said encoded signals, parameter control meansfor using said received encoded signals to adjust said parameter inresponse to said user's heart rates if said received encoded signals arefrom said transmitter.
 46. The apparatus of claim 45, further includinga display means on said exercise equipment for displaying said user'sheart rates.
 47. The apparatus of claim 45, further including means fordetecting errors in said encoded signals representing heart rates. 48.The apparatus of claim 47, further including means in said receiver forusing only encoded signals from said transmitter for controlling saidparameter control means.